Background: Baloxavir marboxil is a novel class of antiviral agent for influenza, introduced into clinical practice in 2018. A concern remains about the variant virus with reduced susceptibility after baloxavir exposure and its clinical consequences including healthcare seeking behavior. Methods: Using a healthcare database in Japan, we compared the medical resource use following baloxavir and neuraminidase inhibitors (NAIs) treatment among children aged 7- 15 years. Study period was from December 2018 to March 2019. The primary endpoint was the composite of hospitalization, laboratory and radiological tests, and antibiotic use over 1-9 days of antiviral treatment. As prespecified exploratory analyses, secondary outcomes were assessed and subgroup analyses comparing baloxavir with each NAI were done. Results: Data from 115 867 prescriptions in 115 238 children were analyzed (median age: 10 years, risk of severe influenza in 26%, baloxavir accounting for 43%). Overall, baloxavir use did not increase the subsequent medical resource utilization in the composite endpoint (adjusted odds ratio [aOR]: 1.002; 95% confidence interval [CI]: 0.999–1.005; P= .16), as were likelihoods of other secondary outcomes. In the subgroup analysis, baloxavir use was associated with higher medical resource use than oseltamivir (aOR: 1.011; 95% CI: 1.007–1.015; P < .001) and lower resource use than zanamivir (aOR: 0.995; 95% CI 0.991–0.999; P= .039). Conclusions: Prescribing baloxavir rather than NAIs did not increase medical resource utilization within 9 days of treatment, except in one exploratory comparison with oseltamivir. Our data were derived from single-year observation in one country, thereby requiring future researches.